Colors in reflections change slightly just as value did. You will notice that a bright, vivid color is slightly more dull in the reflection. If you make both the values and colors in the water the same as the actual objects being reflected, then your water might not look as real as it could.
There are other things we can do to make our water look more realistic as well. The way you paint the shapes in reflections can tell your viewer how much movement there is in the water. A perfect reflection with no visible distortion tells everyone that the water is calm. A slightly jagged or distorted reflection will tell people that there is some movement in the water. Finally, a very rough and distorted reflection is an indication of water that is flowing quickly over a rough surface.